Volumetric Measurement Device, System and Method

ABSTRACT

An acoustic volume sensing device is disclosed. The device includes a housing comprising a reference volume chamber and a variable volume chamber, the reference volume chamber and the variable volume chamber connected by a resonant port, a first MEMS microphone located in acoustic relation to the variable volume chamber, a second MEMS microphone located in acoustic relation to the reference volume chamber, a MEMS speaker located in acoustic relation to the reference volume chamber, and a circuit board in electric connection with the first and second MEMS microphones and the MEMS speaker.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Non-Provisional Application which claimsthe benefit of U.S. Provisional Patent Application Ser. No. 61/607,880,filed Mar. 7, 2012 and entitled Volumetric Measurement Device, Systemand Method (Attorney Docket No. J28), which is hereby incorporatedherein by reference in its entirety.

FIELD OF THE INVENTION

This application relates generally to volumetric measurement, and moreparticularly to volumetric measurement devices, systems and methods.

BACKGROUND

Many potentially valuable medicines or compounds, including biologicals,are not orally active due to poor absorption, hepatic metabolism orother pharmacokinetic factors. Additionally, some therapeutic compounds,although they can be orally absorbed, are sometimes required to beadministered so often it is difficult for a patient to maintain thedesired schedule. In these cases, parenteral delivery is often employedor could be employed.

Effective parenteral routes of drug delivery, as well as other fluidsand compounds, such as subcutaneous injection, intramuscular injection,and intravenous (IV) administration include puncture of the skin with aneedle or stylet. Users of parenterally delivered drugs may benefit froma wearable device that would automatically deliver neededdrugs/compounds over a period of time.

To this end, there have been efforts to design devices, includingportable and wearable devices, for the controlled release oftherapeutics. Such devices are known to have a reservoir such as acartridge, syringe, or bag, and to be electronically controlled. Thesedevices suffer from a number of drawbacks including the malfunctionrate. Reducing the size, weight and cost of these devices is also anongoing challenge. Additionally, these devices often do not determinethe volume of fluid delivered.

SUMMARY OF THE INVENTION

In accordance with one implementation, an acoustic volume sensing deviceis disclosed. The device includes a housing comprising a referencevolume chamber and a variable volume chamber, the reference volumechamber and the variable volume chamber connected by a resonant port, afirst MEMS microphone located in acoustic relation to the variablevolume chamber, a second MEMS microphone located in acoustic relation tothe reference volume chamber, a MEMS speaker located in acousticrelation to the reference volume chamber, and a circuit board inelectric connection with the first and second MEMS microphones and theMEMS speaker.

Some embodiments of this aspect of the invention include one or more ofthe following. Wherein the device further includes a hydrophobic,substantially acoustically transparent mesh device located in theresonant port. Wherein the first and second MEMS microphone and MEMSspeaker are integrated into a single package.

In accordance with one implementation a method for determining a volumeof fluid that has exited a measurement chamber is disclosed. The methodincludes completing an acoustic volume sensing measurement of ameasurement chamber where the measurement chamber is at a firstpredetermined pressure, pumping fluid into the measurement chamber untilthe measurement chamber reaches a second predetermined pressure,completing an acoustic volume sensing measurement of a measurementchamber where the measurement chamber is at the second predeterminedpressure, reducing the measurement chamber pressure to the firstpredetermined pressure, and completing an acoustic volume sensingmeasurement of a measurement chamber where the measurement chamber is atthe second predetermined pressure.

In accordance with one implementation, an acoustic volume measurementdevice is disclosed. The acoustic volume measurement device including aport comprising a hydrophobic, substantially acoustically transparentmesh device located in the port.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features and advantages willbecome apparent from the description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of one method according to one embodiment;

FIG. 2 is an illustrative view of one embodiment of an AVS device;

FIG. 3 is an exploded view of one embodiment of an AVS measurementassembly;

FIG. 4 is a block diagram of one method according to one embodiment;

FIG. 5 shows an illustrative view of an embodiment for MEMS AVS; and

FIG. 6 shows an illustrative view of an embodiment for MEMS AVS.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

Various embodiments of Acoustic Volume Sensing (AVS) are included hereinas embodiments of AVS. These embodiments include, but are not limitedto, those described in U.S. patent application Ser. No. 11/704,899,filed Feb. 9, 2007 and entitled Fluid Delivery Systems and Methods, nowU.S. Published Application No. US-2007-0228071, published Oct. 4, 2007(Attorney Docket No. E70), which is hereby incorporated herein byreference in its entirety, and U.S. patent application Ser. No.12/981,350, filed Dec. 29, 2010 and entitled Infusion Pump Assembly, nowU.S. Published Application No. US-2011-0190694, published Aug. 4, 2011(Attorney Docket No. 140), which is hereby incorporated herein byreference in its entirety. Various embodiments include using AVS todetermine the volume of a fluid delivered by determining a first volumein a chamber, pumping fluid from the chamber, then determining a secondvolume in the chamber, and calculating the volume of fluid delivered.This calculation may be used in conjunction with various devices,including, but not limited to, infusion pumps which may include, but arenot limited to, IV infusion pumps and/or wearable infusion pumps, forexample, insulin pumps.

U.S. patent application Ser. No. 13/725,790, filed Dec. 21, 2012 andentitled System, Method, and Apparatus for Infusing Fluid (AttorneyDocket No. J76) is hereby incorporated herein by reference in itsentirety. The various AVS related structures/devices described togetherwith the related description, may be incorporated, fully or partially,into any type of device, for example, including but not limited to,wearable infusion pumps. Thus, AVS may be used with respect to variousdevices which include, but are not limited to, infusion pumps and microinfusion pumps.

With respect to the various embodiments of AVS and the various deviceconfigurations that may be used with respect to AVS measurement, in someembodiments, all of the AVS measurements may be taken at knownpressures. For example, in some embodiments, the various AVSmeasurements may be calculated at different pressures so that if thereis air present in the chamber, the air will be identified. Thus, in someembodiments, an AVS measurement may be taken at one pressure, then,without moving the fluid, the AVS measurement may be taken at another,different pressure. Using this technique, air bubbles may be detected.Thus, in some embodiments, AVS may be used to detect air bubbles.

In some embodiments, the AVS measurements may be taken at the samepressure. In these embodiments, thus, if there is air present in the AVSchamber, the air will not be compressed between the first, second, etc.,measurements and therefore, the air does not affect the accuracy of thevolumetric measurement. In some embodiments, the AVS measurements may betaken at zero pressure.

Referring now to FIG. 1, in some embodiments, downstream from the AVSmeasurement chamber may be a restrictive pathway so as to reduce thepressure within the AVS measurement chamber slowly. For example, amethod may be used for determining the volume of fluid exiting an AVSmeasurement chamber. This method 100 may, in some embodiments, includewhere the AVS measurement chamber may be at a first predeterminedpressure, e.g., 5 pounds per square inch (“PSI”) and an AVS volumemeasurement of AVS measurement chamber may be completed 102. Fluid maythen be pumped into the AVS measurement chamber to a secondpredetermined pressure 104, e.g. 10 PSI. Another AVS measurement iscompleted 106. Next, the pressure in the AVS measurement chamber isreduced, slowly, to the first predetermined pressure 108, e.g. 5 PSI.Another AVS measurement is then taken 110. In various embodiments, thepredetermined pressures may be greater than or less than the examplesgiven herein. However, in various embodiments, the first predeterminedpressure is less than the second predetermined pressure.

In some embodiments, the AVS measurement chamber may include adownstream active check valve with a cracking pressure equal to thefirst predetermined pressure, e.g. 5 PSI, thus, the valve will closewhen the pressure falls below the second predetermined pressure, e.g. 5PSI. In some embodiments, a pump may be introduced into the AVSmeasurement chamber. Some embodiments may include a downstream activecheck valve and a restrictive pathway. Some embodiments may include arestrictive pathway.

Thus, using this method, the volume of fluid that flowed out of the AVSmeasurement chamber may be determined.

Referring now to FIG. 2, in some embodiments of the various embodimentsof AVS, a membrane or mesh cover may be installed into the port toprevent unwanted debris and fluid from entering the port. In someembodiments, a screen may be used. In some embodiments, the screen maybe a hydrophobic screen, in other embodiments; the screen may be aporous material. In some embodiments, the screen may be a mesh material.In some embodiments, a hydrophobic membrane may be used. In variousembodiments, the screen is substantially acoustically transparenttherefore, not affecting the accuracy of the volumetric measurement.Referring to FIG. 2, an illustrative view of one embodiment of an AVSdevice 202 with a mesh screen 200 is shown. In some embodiments, thespring 628 may not be used in the AVS device 202. The AVS device 202 mayinclude a reference volume 204, a variable volume 206 and a resonantport 208. Other elements may also include a microphone in the referencevolume, a speaker in the reference volume and a microphone in thevariable volume. The AVS device 202 determines the volume of fluid(which may include liquid and/or gas) in the variable volume 206. Invarious embodiments, the AVS device 202 may be used to determine thevolume of fluid (which may include liquid and/or gas) in the variablevolume 206, then an additional volume of fluid may be pumped orotherwise may enter the variable volume 206, then AVS device 202 maydetermine the volume of fluid (which may include liquid and/or gas) inthe variable volume 206, then, the volume of fluid may exit the variablevolume 206. Next, AVS device 202 may determine the volume of fluid(which may include liquid and/or gas) in the variable volume 206. Usingthese measurements, the volume of fluid that exited the variable volume206 may be determined.

In various embodiments where a mesh barrier is used, the mesh barriermay be attached to the port area such that the mesh barrier is notcompliant/non-movable. Referring now also to FIG. 3, in someembodiments, a mesh screen 630 may be sandwiched between the spring 628and the ring 1406. In various embodiments, the mesh screen 630 may bemade from any hydrophobic, substantially acoustically transparentmaterial. In some embodiments, the mesh screen 630 may be a POREX plug,for example, using POREX made by POREX Corporation, Fairburn, Ga.,U.S.A. In some embodiments, the spring may not be used in the AVSdevice. The AVS device 148 also includes an upper housing 1400, speakerassembly 622, reference microphone 626, seal assembly 1404, lowerhousing 1402, port assembly 624, spring diaphragm 628, and retainingring assembly 1406. In some embodiments, a spring diaphragm may not beincluded.

Referring now to FIG. 4, in some embodiments, the AVS measurement method400 may include sampling one frequency 402 and watching that onefrequency move. For example, where in some embodiments of AVS, resonanceis measured by measuring gain, damping and spring rate/volume. In theseembodiments, a full sine sweep is used to estimate the three values forgain, damping and spring rate/volume, respectively. In some embodiments,assuming two of the three values/parameters remain constant 404 andassuming one of the three values/parameters is changing 406, by watchingthat particular frequency going forward 408, from that one point thevolume may be estimated 410. Thus, in some embodiments, using thismethod, volume calculation using AVS may be performed morequickly/efficiently. Although, in various embodiments, this measurementmay not be completed in real time, estimated volume measurement may bedesirable for many reasons, including, but not limited to, the abilityto review what is happening while things are moving.

Referring now also to FIG. 5, in some embodiments, the speaker used inthe AVS device may be a traditional voice coil. However, in someembodiments, a MEMS device may replace the speaker in the AVS device.For example, in some embodiments, a microelectomechanical system(“MEMS”) device that generates sound using an electrostatic element maybe used in an AVS device 500. In some embodiments, the MEMS device thatgenerates sound using an electrostatic element may be similar to a MEMSmicrophone. The AVS device 500, in some embodiments, may include an AVShousing 516. The components of the AVS are located within the AVShousing 516. In some embodiments, therefore, the AVS device 500 mayinclude a reference volume chamber 502, a variable volume chamber (orvolume measurement chamber) 504, MEMS microphones 506, 508, a MEMSspeaker 510, a resonant port 512 and a circuit board 514.

Referring now to FIG. 6, another embodiment of an AVS device 600 isshown. In some embodiments, the speaker used in the AVS device may be atraditional voice coil. However, in some embodiments, a MEMS device mayreplace the speaker in the AVS device. For example, in some embodiments,a MEMS device that generates sound using an electrostatic element may beused in an AVS device 600. In some embodiments, the MEMS device thatgenerates sound using an electrostatic element may be similar to a MEMSmicrophone. In some embodiments, MEMS microphones 602, 604 and the MEMSspeaker 606 are integrated into a single package or device with the MEMSmicrophones 602, 604 on alternate sides of the package/device. The AVSdevice 600, in some embodiments, may include an AVS housing 608. Thecomponents of the AVS are located within the AVS housing 608. In someembodiments, therefore, the AVS device 600 may include a referencevolume chamber 612, a variable volume chamber (or volume measurementchamber) 614, MEMS microphones 602, 604, a MEMS speaker 606, a resonantport 616 and a circuit board 610.

In some embodiments of the AVS device 600, the AVS housing 608 may beintegrated into the MEMS package/device. The MEMS package, in someembodiments, may integrate the reference chamber 612 and variablechamber 614 as well as the resonant port 616. Thus, in some embodiments,the first and second MEMS microphones 602, 604 and MEMS speaker 606 arealso integrated with the reference chamber 612, variable chamber 614 andresonant port 616.

Still referring to FIG. 6, in some embodiments, the package/device asdescribed above may also include, but is not limited to, one or more ofthe following: a thermistor, analog electronics for driving the speaker606, signal conditioning for the microphones 602, 604, and/or a DSP fordriving AVS. In some embodiments, various embodiments of the package mayalso be used in active noise cancellation headsets.

A number of embodiments have been described. Nevertheless, it will beunderstood that various modifications may be made. Accordingly, otherembodiments are within the scope of the following claims.

While the principles of the invention have been described herein, it isto be understood by those skilled in the art that this description ismade only by way of example and not as a limitation as to the scope ofthe invention. Other embodiments are contemplated within the scope ofthe present invention in addition to the exemplary embodiments shown anddescribed herein. Modifications and substitutions by one of ordinaryskill in the art are considered to be within the scope of the presentinvention.

What is claimed is:
 1. An acoustic volume sensing device comprising: ahousing comprising a reference volume chamber and a variable volumechamber, the reference volume chamber and the variable volume chamberconnected by a resonant port; a first MEMS microphone located inacoustic relation to the variable volume chamber; a second MEMSmicrophone located in acoustic relation to the reference volume chamber;a MEMS speaker located in acoustic relation to the reference volumechamber; and a circuit board in electric connection with the first andsecond MEMS microphones and the MEMS speaker.
 2. The device of claim 1further comprising comprising a hydrophobic, substantially acousticallytransparent mesh device located in the resonant port.
 3. The device ofclaim 1 wherein the first and second MEMS microphone and MEMS speakerare integrated into a single package.
 4. A method for determining avolume of fluid that has exited a measurement chamber, the methodcomprising: completing an acoustic volume sensing measurement of ameasurement chamber where the measurement chamber is at a firstpredetermined pressure; pumping fluid into the measurement chamber untilthe measurement chamber reaches a second predetermined pressure;completing an acoustic volume sensing measurement of a measurementchamber where the measurement chamber is at the second predeterminedpressure; reducing the measurement chamber pressure to the firstpredetermined pressure; and completing an acoustic volume sensingmeasurement of a measurement chamber where the measurement chamber is atthe second predetermined pressure.